She died. It has been the teaching of the Church from the beginning. I did a small writeup when I was Eastern Catholic defending the Eastern Catholic/Orthodox tradition of the Dormition of the Theotokos. The document that dogmatized the Assumption mentions Mary’s death several times, even from Roman Catholic sources. It was never removed as part of the faith that Mary died. She died and was resurrected and assumed. She is the fulfillment of God’s plan of salvation, and our hope that the same fate awaits us.
Blessed Pope John Paul II also said that the reason Munificentissimus Deus does not categorically state “After Mary died” is NOT because it is an open question to Catholics. The reason was that they didn’t want to make other dogmatic statements to cloud the issue of the Virgin Mary’s Assumption. IOW, it just wasn’t the place to get into the whole dogmatic decree of Mary’s death. JPII went on to say that Mary DID in fact die, in order to conform more perfectly with her Son.
Link to speech
So the Catholic Church has ALWAYS taught that the Virgin Mary died. It wasn’t until recent times, ESPECIALLY after Munificentissimus Deus, that the whole issue of Mary not dying has gained traction.
There are very real difficulties with that whole scenario, not just doctrinally, but logistically speaking. In a nutshell:
Were there witnesses to Mary just being Assumed while still living?
Because if there weren’t, then that would have caused great distress among all of the Apostles and Disciples that something bad had happened. Somebody like the Mother of God suddenly becomes a missing person in a hostile world? This scenario is the most unbelievable, and does not bear the stamp of a Divine event.
OR,
There were witnesses, and yet, unlike normal witnesses they never gave testimony to the great event? That as well is very unlikely, as there is NO ancient tradition of Mary being assumed alive. The Ancient tradition is that she died.
Now some may have the same objection to her Assumption. But the lack of ANY disturbance in the ancient apostolic Church, regarding the disappearance of the BVM, renders the likelihood of witnesses to her death very probable. That is normative, and unremarkable.
Let us further consider whether it be true, as the legends say, that the Apostles discovered her tomb to be empty after 3 days. Why was that not published? I would say because they did not actually WITNESS her Assumption, but through Divine Inspiration understood the MEANING of her empty grave, and because it would possibly be a distraction in their spreading of the true Gospel message of the Resurrection of the Lord. In this scenario, we would have exactly what we DO have today. A tradition of Mary dieing, and a tradition that she was Assumed into heaven, although it is shrouded in a certain amount of mystery from the world at large by the lack of any Scriptural account. IOW, only the Church was able to reveal this Divine mystery.